Why in the News?
Following the tragic crash of the Air India Boeing 787 Dreamliner in Ahmedabad, authorities concluded the identities of the victims using DNA analysis.
What is DNA?
- Overview: DNA (Deoxyribonucleic Acid) is the molecule that carries genetic instructions essential for the development, growth, and reproduction of all living organisms.
- Location in the Body: It is present in nearly every human cell and is unique to each person, except for identical twins.
- Structure: DNA is made up of four chemical bases—Adenine (A), Cytosine (C), Guanine (G), and Thymine (T)—arranged in sequences that encode genetic data.
- Biological Fingerprint: Due to its individual uniqueness, DNA acts like a biological fingerprint, useful in crime investigations and disaster victim identification.
How DNA Identification Works?
- Use in Forensics: DNA is extracted from human remains when visual identification is not possible due to burns, decomposition, or trauma.
- Reference Matching: Extracted DNA is compared with:
- Family reference samples (from parents, children, siblings)
- Personal belongings (like a toothbrush, razor, or hairbrush)
- Sample Reliability: Bones and teeth are preferred in degraded conditions, as they preserve DNA more effectively.
- Forensic Accuracy: Specialized forensic labs analyze and match DNA sequences, confirming identity with high levels of accuracy.
Common DNA Analysis Methods:
- Short Tandem Repeat (STR) Analysis:
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- Focuses on short, repeating sequences of DNA that vary among individuals.
- Requires nuclear DNA, typically from well-preserved samples.
- Considered the gold standard for forensic identification.
- Mitochondrial DNA (mtDNA) Analysis:
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- Extracts DNA from mitochondria, not the nucleus, making it more resilient in degraded samples.
- Inherited only from the mother, allowing tracing through the maternal lineage.
- Y-Chromosome Analysis:
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- Targets Y chromosomes, passed from father to son.
- Useful for identifying male victims when paternal relatives are available.
- Single Nucleotide Polymorphism (SNP) Analysis:
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- Detects single-letter changes in the DNA sequence.
- Applied when DNA is highly degraded and other methods are less effective.
- Can be used with reference items like personal hygiene tools.
| [UPSC 2000] Assertion (A): DNA Finger-printing” has become a powerful tool to establish paternity and identity of criminals in rape and assault cases. Reason (R): Trace evidence such as hairs, saliva and dried semen are adequate for DNA analysis.
Options: (a) Both A and R are true, and R is the correct explanation of A (b) Both A and R are true, but R is not a correct explanation of A (c) A is true, but R is false (d) A is false, but R is true |
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